The dance of peace has begun. The first step came last week when the British and Irish governments published their joint blueprint for the implementation of the Good Friday agreement. On the surface that looked like the greenest document London and Dublin had ever presented on Northern Ireland; rejectionist unionists trashed it accordingly.

But the words on the page were deceptive. The huge gains offered to republicans - on police reform and scaling down Britain's military presence in the province - were spelled out in writing; the price republicans would have to pay to earn them was not. Instead, the move demanded of republicans - their quid for the British and unionist quo - was left unstated. But it was clearly part of the bargain struck in the last few, tough weeks of negotiations. That move, put simply, was decommissioning.

Yesterday it came, in the form of the peace dance's second step. The independent decommissioning body, headed by the Canadian former general, John de Chastelain, delivered its most hopeful assessment yet of the IRA's intentions. The general said he was satisfied that the Provisionals had begun a process that would put their arms "completely and verifiably beyond use".

As both the Irish prime minister and Sinn Fein's Gerry Adams said afterwards, that represents a huge, historic step by the republican movement. For yesterday's words were not spoken by the IRA - even if they did deploy the same exact language the Provos use to discuss decommissioning.

These were the words of the man agreed by all parties to act as the ultimate arbiter of Northern Irish disarmament. He, and not some republican propagandist, is now convinced that the IRA will put its weapons away wholly and forever. We cannot know what the IRA representative did to persuade the decommissioning body, but if it is good enough for the general, it should be good enough for everyone else.

The second move of the peace dance is complete: the two governments have promised to implement the 1998 accord in full and now the IRA has promised to put away its arsenal. This is the breakthrough Northern Ireland has sought for nearly a decade.

The third step now belongs to the unionists. David Trimble has rightly recognised yesterday's news as "significant" and will await developments. We wished he would, just for once, rise to the occasion and celebrate what a great achievement this marks for the peace process and, therefore, for him. But that is not Mr Trimble's style. Perhaps that is wise: he has to take his people with him.

The Ulster Unionist leader says he needs to see not just a promise from the IRA - albeit one accepted by Gen de Chastelain - but actual decommissioning. Our front-page story today suggests such a move could come within the next month or so, as the international inspectors, Cyril Ramaphosa and Martti Ahtisaari announce, through Gen de Chastelain, that they have seen IRA dumps destroyed before their very eyes.

Such a declaration should swiftly answer the unionists' remaining two anxieties about decommissioning: its timing and the mystery that surrounds its method.

If such a move is not enough for unionists, and Jeffrey Donaldson and friends continue to raise new objections - even in the face of the extraordinary shift by republicans confirmed yesterday - then one will have to doubt those unionists' commitment to the very idea of power-sharing, as enshrined in the Good Friday pact.

For now, at last, peace is within Northern Ireland's grasp. Every partner in the dance just has to reach for it.